From what I gather, space() searches for a free place that is a circle with given radius (the dist parameter). When a free space is found, it is guaranteed not to have any items within that circle. When searching for a space to drop items, this controls how densely they will be placed. Small radius will result in denser item placement while bigger radius will result in quite a spread. You can see how it works if you add a parameter to space() in CollectTitanium3().

"After three days without programming, life becomes meaningless."
~The Tao of Programming